Ok. It’s been a while since I’ve done this, but I think I understand. So, if you were to add Angle A and Angle B together in figure 1, you would get 83 degrees. And 180-83=97. Notice how angle C in figure 2 is also 97 degrees. Because of this, one can figure out that the two triangles are congruent. I’m not sure if this is all of the evidence that you’d need to solve this problem completely, but I hope this helps!